CCI DRAG® Velocity Control Eliminates Vibration Problems at Hope Creek

Hope Creek Generating Station is a thermal nuclear power plant located in Hancocks Bridge, New Jersey. The plant is owned and operated by PSEG Nuclear LLC and has one BWR reactor with generating capacity of 1,049 MWe. The plant came online on July 25, 1986, and is one of only four nuclear power units in New Jersey (the others are the two at the Salem Generating Station, and the Oyster Creek Nuclear Generating Station) - together they produce over half of the electricity consumed by New Jersey.

During Hope Creek ’s last operating cycle, vibration issues were experienced with the 5A and 6A Feed Water Heaters (FWH) and the associated piping. Efforts to alleviate the problem led to the removal of the 6A FWH from service and consequently resulted in a 10MWe loss of power production over that period. Investigation into the cause of the vibration was undertaken during a scheduled outage, focusing on suspected internal damage to the 6A FWH level control valve, but additional inspections were also performed on all potential causes like the internals of the 5A and 6A FWHs. The results of the inspections determined that the FWHs are satisfactory with no identified issues and in actual fact, the level control valve was the cause of the vibration.

Inspection of the disruptive level control valve revealed that the connection between the stem and plug was damaged. To achieve long term performance, velocity through the valve must be controlled at all times. High fluid velocity through the valve trim leads to cavitation, erosion and vibration that can damage equipment and result in system control problems.

CCI supplied Hope Creek with a DRAG® multistage, disk stack valve to resolve the vibration problems. The original valve’s single stage control valve design did not control fluid velocity through the valve internals which resulted in fluid acceleration, high velocity and low pressure through the valve trim and inlet reducer. This led to the damaging cavitation and vibration. In order to ensure two phase flow is eliminated fluid velocity needs to be less than 50ft/s in the valves internals. The superior DRAG® valve’s multi–path, multi-stage design controls the fluid kinetic energy by controlling fluid velocity at all times within the valve internals to 20ft/s, ensuring that the recurrence of the problem is prevented.

Published in SOLUTIONS Fall 2006